Method for controlling combined lathe apparatus, combined lathe apparatus, turning tool holder, blade position registering apparatus, and blade position detecting apparatus

ABSTRACT

A carriage is moved in a direction including a Y axis component in order to move a turning process tool that is attached to a tool spindle along a horizontal line that is perpendicular to a Z axis, and thus, a turning process is carried out on a workpiece which is attached to a workpiece spindle.

This application is a divisional of pending U.S. patent application Ser.No. 12/121,115, filed May 15, 2008, which claims the benefit of JapanesePatent Application No. 2007-130992, filed May 16, 2007, the entiredisclosures of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to a method for controlling a combinedlathe apparatus, a combined lathe apparatus, a turning tool holder, ablade position registering apparatus, and a blade position detectingapparatus.

The basic design concepts for combined lathe apparatuses include thefollowing 1) to 3).

These are the most important points which should be taken intoconsideration at the time of design.

1) The operator can come close to a workpiece and the tool headstock,which is easy to use.

2) The space for installing the machine tool within a factory is small.

3) Chips can be smoothly discharged and the chips are easy to beprocessed.

Thus, as shown in FIGS. 12(A) to 12(C), apparatuses having a moveablebody 420, which is inclined by a predetermined angle θ relative to thehorizontal line, have been used as a combined lathe apparatus having anautomatic tool replacing apparatus. In general, the predetermined angleθ is 45°, 60°, or 90°. The moveable body 420 is placed above a bed 410and a tool headstock 400 which is moveable along the X axis is providedon the moveable body 420. In the example in FIG. 12(A), the moveablebody 420 moves along the horizontal line Yt and the tool headstock 400moves along the X axis which makes a predetermined angle θ with respectto the horizontal line Yt. The horizontal line Yt is a straight lineincluded in the horizontal plane and the X-Y plane.

In the example in FIG. 12(B), the moveable body 420 moves along the Yaxis and the tool headstock 400 moves along the X axis which makes thepredetermined angle θ with respect to the horizontal line Yt. In theexample in FIG. 12(C), the moveable body 420 moves along the Y axis(horizontal line Yt) and the tool headstock 400 moves along the X axiswhich is perpendicular to the horizontal line Yt.

In this type of combined lathe apparatuses, a workpiece is cut at apredetermined angle θ, and thus a turning process is carried out on theworkpiece. In the combined processing lathe disclosed in JapaneseLaid-Open Patent Publication No. 2000-254802, for example, a tool whichis placed in the direction perpendicular to the axis of the workpiecespindle is used to process the workpiece in order to avoid the effectsof the thermal displacement of the workpiece spindle.

In the case where a turning process is carried out on the outerperipheral surface of a workpiece in the above described combined latheapparatus having automatic tool replacing means, a problem arises thatbending of the workpiece due to its own weight directly affects theprocess precision (cylindricity). In general, the amount of bending δ(mm) in a supported workpiece can be calculated in Formula (1).

δ=(5·P·L ³)/(384·E·I)  (1)

P is the weight of the workpiece (N), L is the length of the workpiece(mm), E is a modulus of direct elasticity (N/mm²), and I is the secondmoment of area (mm⁴). Formula (1) includes the cubed length L of theworkpiece. Therefore the length L of the workpiece is very dominant overthe amount of bending δ. Thus, the greater the length L of the workpieceis, the greater the amount of bending δ due to the weight of theworkpiece becomes. Accordingly, when a turning process is carried out ata predetermined angle θ relative to the horizontal line Yt, it issubjected to the effects of the workpiece bending, and therefore theprecision of processing the workpiece becomes poor (hereinafter thisproblem is referred to as first problem).

In terms of the general structure of the bed, the thickness in thevertical direction is small and the length in the lateral direction isgreat for the ease of use. In the case of a machine tool, the jack boltis adjusted so that the machine tool is positioned. However, thelocation of the base changes and the load applied to the jack bolt alsochanges because of the occurrence of an earthquake, a change in thestate of the base made of concrete on which the machine tool isinstalled and the like. Therefore the degree of bending in the verticaldirection of the bed which is thin and has a low rigidity is easy tochange in machine tools.

A change in the degree of bending in the vertical direction means thesame as a change in pitching as shown in FIG. 15. Pitching means adeviation in the angle when the tool headstock moves along the axis ofthe workpiece spindle. The amount of bending δ is due to the workpiece Wbending in the case where the error on the machine side is “0”, and thepitching is due to an error in the machine.

This error affects the position of the blade in the vertical directionand at the same time affects the precision of processing the workpiece W(hereinafter this problem is referred to as second problem). In the casewhere this problem is addressed by readjusting the jack bolt, a greatamount of time and effort are required for the adjustment. In additionto this, it is difficult to determine whether or not the change in thestate of the base has lowered the precision.

Furthermore, a rotating tool, a turning processing tool and the like areattached to the tool headstock in accordance with contents ofprocessing. A motor for rotating the rotating tool, a bearing forsupporting an object to be rotated and the like are incorporated in thetool headstock. In this case, the motor and the bearing are the heatsource which causes a thermal displacement in the tool headstock. Thethermal displacement is easily caused along the axis of the spindle ofthe tool. As shown in FIG. 14, the direction of the axis of the spindleof the tool coincides with the direction of cutting in which theworkpiece is processed using a turning processing tool. That is to say,the turning processing tool is subjected to the effects of the thermaldisplacement in the tool headstock even after the rotating tool isreplaced with the turning processing tool. In FIG. 14, Wa indicates theouter diameter of the workpiece W on which a cutting process has beencarried out in such a state as to be subjected to thermal displacement.In FIG. 14, q indicates the length gained by subtracting the outerdiameter Wa of the workpiece W on which a cutting process has beencarried out in such a state as to be subjected to thermal displacementfrom the outer diameter of the workpiece W on which a cutting processhas been carried out in such a state as not to be subjected to thermaldisplacement.

Accordingly, thermal displacement in the turning processing tool affectsthe precision of processing in an outer diameter turning process and theouter diameter of the workpiece W after processing (hereinafter thisproblem is referred to as third problem). A technology for allowing amachine to correct the amount of thermal displacement has been proposed.In accordance with this technology, however, no fundamental measure istaken against the problem and therefore it is difficult to stably carryout a turning process with high precision.

The combined processing lathe disclosed in Japanese Laid-Open PatentPublication No. 2000-254802 does not have an automatic tool replacingapparatus where a rotating tool and a turning processing tool can bereplaced. Therefore, the first to third problems with combined processlathing apparatuses having an automatic tool replacing apparatus towhich the present invention relates cannot be solved at the same time.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a method forcontrolling a combined lathe apparatus having automatic tool replacingmeans, which method suppresses the effects of a workpiece bending due toits own weight, the effects of pitching due to a change in the manner inwhich the bed having a low rigidity bends in the vertical direction, andthe effects of thermal displacement due to heat from a motor andbearings for rotating a rotating tool.

Another object of the present invention is to provide a combined latheapparatus having automatic tool replacing means, which apparatussuppresses the effects of a workpiece bending due to its own weight, theeffects of pitching due to a change in the manner in which the bedhaving low rigidity bends in the vertical direction, and the effects ofthermal displacement due to heat from a motor and bearings for rotatinga rotating tool.

Still another object of the present invention is to provide a turningtool holder which is used in accordance with the method for controllinga combined lathe apparatus having an automatic tool replacing means andused in the combined lathe apparatus having an automatic tool replacingmeans. Yet another object of the present invention is to provide a bladeposition registering apparatus which is used in the combined latheapparatus having an automatic tool replacing means. Still yet anotherobject of the present invention is to provide a blade position detectingapparatus which is used in the combined lathe apparatus having anautomatic tool replacing means.

To achieve the foregoing objectives and in accordance with a firstaspect of the present invention, a method for controlling a combinedlathe apparatus is provided. The combined lathe apparatus includes aworkpiece spindle on which a workpiece is mounted, a tool spindle towhich a turning process tool for carrying out a turning process on theworkpiece is removably attached, automatic tool replacing means fortaking out a specific turning process tool from among a plurality ofturning process tools and replacing the turning process tool attached tothe tool spindle with the specific turning process tool, a movable bodywhich is movable along a second axis which is perpendicular to a firstaxis that is the axis of the workpiece spindle and forms a predeterminedangle θ (0<θ≦90°) with a horizontal plane, and a tool headstocksupported by the movable body. The tool headstock has the tool spindle.The movable body is movable in a direction including a third axiscomponent which is perpendicular to the first axis and the second axis.The tool spindle can be controlled to be rotated or held without beingrotated. A turning process is carried out on the workpiece attached tothe workpiece spindle by moving the movable body in a directionincluding the third axis component in order to move a cutting point ofthe turning process tool attached to the tool spindle along a horizontalline which is perpendicular to the first axis, or by moving the movablebody in a direction including the third axis component, and at the sametime, moving the tool headstock along the second axis.

In accordance with a second aspect of the present invention, a combinedlathe apparatus is provided that includes a workpiece spindle on which aworkpiece is mounted, a tool spindle to which a turning process tool forcarrying out a turning process on the workpiece is removably attached,automatic tool replacing means for taking out a specific turning processtool from among a plurality of turning process tools and replacing theturning process tool attached to the tool spindle with the specificturning process tool, a movable body which is movable along a secondaxis which is perpendicular to a first axis that is the axis of theworkpiece spindle and forms a predetermined angle θ (0<θ≦90) with ahorizontal plane, a tool headstock supported by the movable body. Thetool headstock has the tool spindle, and control means for controllingmovement of the movable body. The movable body is movable in a directionincluding a third axis component which is perpendicular to the firstaxis and second axis. The tool spindle can be controlled to be rotatedor held without being rotated. The control means carries out a turningprocess on the workpiece attached to the workpiece spindle by moving themovable body in a direction including the third axis component in orderto move the cutting point of the turning process tool attached to thetool spindle along a horizontal line which is perpendicular to the firstaxis, or by moving the movable body in a direction including the thirdaxis component, and at the same time, moving the tool headstock alongthe second axis.

In accordance with a third aspect of the present invention, a turningtool holder that is removably and coaxially attached to a tool spindlethat forms a predetermined angle θ with a horizontal plane is provided.The turning tool holder is provided with a holder main body on which aturning tool having a turning tip is mounted. The holder main body has aturning tool attachment surface on which the turning tool is attached.The angle formed between the turning tool attachment surface and theaxis of the holder main boy is equal to the predetermined angle θ formedbetween the axis of the tool spindle and a horizontal plane.

In accordance with a fourth aspect of the present invention, a bladeposition registering apparatus for registering the position of the bladeof the turning process tool which is provided in the combined latheapparatus according to the second aspect of the present invention isprovided. A reference point is provided on the axis of the tool spindle.The blade position registering apparatus includes blade positioninputting means and storage means. The blade position inputting meansinputs a first tool length which is an amount of offset by which theblade of the turning process tool is offset from the reference pointalong the first axis, a second tool length which is an amount of offsetby which the blade of the turning process tool is offset from thereference point along a horizontal line which is perpendicular to thefirst axis, and a third tool length which is an amount of offset bywhich the blade of the turning process tool is offset from the referencepoint along a vertical line. The storage means stores the inputted firsttool length, the second tool length, and the third tool length.

In accordance with a fifth aspect of the present invention, a bladeposition detecting apparatus is provided that is provided in thecombined lathe apparatus according to the second aspect of the presentinvention, has a plurality of detection surfaces which can make contactwith the blade of the turning process tool, and outputs a detectionsignal when the blade makes contact with one of the detection surfaces.The blade position detecting apparatus includes a first detectionsurface for detecting the blade of the turning process tool which movesalong the axis of the workpiece spindle, a second detection surface fordetecting the blade of the turning process tool which moves along ahorizontal line that is perpendicular to the axis of the workpiecespindle, and a third detection surface for detecting the blade of theturning process tool which moves along a vertical line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a combined lathe apparatusaccording to first to third embodiments of the present invention;

FIG. 2 is an enlarged perspective view showing a portion in the vicinityof the tool headstock of the combined lathe apparatus;

FIG. 3 is a side view showing the combined lathe apparatus;

FIG. 4 is a block diagram showing a control apparatus;

FIG. δ is a diagram illustrating the positional relationship between thecarriage, the tool spindle, the turning tool holder, and the workpiece;

FIG. 6(A) is a diagram for comparing the position of the turningprocessing tool between the prior art and the present embodiment;

FIG. 6(B) is a schematic side view for comparing the position of theturning processing tool between the prior art and the presentembodiment;

FIG. 7 is a diagram illustrating the difference in the cutting pointbetween the prior art and the present embodiment;

FIG. 8 is a perspective view showing a blade position detectingapparatus according to a third embodiment of the present invention;

FIG. 9 is an enlarged side view showing a portion of the blade positiondetecting apparatus;

FIG. 10 is an enlarged perspective view showing a portion of a needlemember;

FIG. 11 is a diagram illustrating cases where a portion of the workpiecewhich is bent is turned and a portion of the workpiece which is not bentis turned;

FIGS. 12(A) to 12(C) are schematic diagrams showing various types ofcombined lathe apparatuses;

FIG. 13 is a diagram illustrating an error in pitching;

FIG. 14 is a diagram illustrating thermal displacement;

FIG. 15 is a diagram illustrating pitching;

FIG. 16 is a graph showing the amount of thermal displacement along theaxis of the spindle of the tool and the amount of thermal displacementin the direction perpendicular to the axis of the spindle of the tool;

FIGS. 17(A) and 17(B) are diagrams illustrating the amount of thermaldisplacement along the axis of spindle of the tool and the amount ofthermal displacement in the direction perpendicular to the axis of thespindle of the tool;

FIG. 18 is a schematic cross-sectional view showing the tool headstock;

FIG. 19 is a table showing a tool registration screen displayed on thedisplay portion;

FIG. 20(A) is a table showing the tool length entry field for tools forX-Z turning displayed on the display portion; and

FIG. 20(B) is a table showing the tool length entry field for tools forhorizontal turning displayed on the display portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

In the following, a combined lathe apparatus and a turning tool holderaccording to one embodiment of the present invention are described withreference to FIGS. 1 to 7.

As shown in FIGS. 1 and 2, a CNC combined lathe apparatus (hereinafterreferred to as combined lathe apparatus) 20 has a bed 21 and a frame 11which are in rectangular parallelepiped form and extend in a Z axis. Afront door 12 is provided on the front surface of the frame 11 so as tobe openable and closeable. A headstock 26 is installed above the bed 21.A workpiece spindle 26 a is supported by the headstock 26 so as to berotatable around an axis O2. The workpiece spindle 26 a is placed insuch a manner that the axis O2 is parallel to the Z axis.

A chuck 26 b is provided in the workpiece spindle 26 a. A workpiece W tobe processed is mounted on the chuck 26 b. A tailstock 27 is placedabove the bed 21 so as to face the headstock 26. The tailstock 27 ismoveable along the Z axis. A tailstock barrel 27 a for supporting an endportion of the workpiece W which is not held by the chuck 26 b isprovided in the tailstock 27 in accordance with the size, shape or typeof process of the workpiece W to be processed.

Furthermore, a known tool magazine 14 is installed on the rear surfaceside of the workpiece spindle 26 a within the frame 11. The toolmagazine 14 contains a turning tool unit which is a turning processingtool, as well as a tool unit such as a rotating tool unit. The turningtool unit is made up of a turning tool 45 and a turning tool holder 40as described below. A known ATC 30 (automatic tool replacing apparatus)is installed in the vicinity of the tool magazine 14. The ATC 30 takesout a tool unit from the tool magazine 14 and mounts it on the belowdescribed tool spindle 25 and dismounts the tool unit that has beenmounted on the tool spindle 25 and places it into the tool magazine 14.

As shown in FIG. 3, a carriage base 22 is attached to the horizontalsurface 21 a of the bed 21. A carriage 23, which is a moveable body, ismounted on the carriage base 22. On the horizontal surface 21 a of thebed 21, the carriage 23 can be moved along the Z axis, which is referredto as longitudinal movement, and can be moved along the projection lineof the Y axis, which is referred to as lateral movement. The lateralmovement corresponds to moving the carriage 23 in the directionincluding a component of the Y axis.

The carriage 23 has a sliding surface 23 a which extends along the Xaxis. The sliding surface 23 a inclines by a predetermined angle θrelative to the horizontal surface 21 a of the bed 21. The predeterminedangle θ may be 45° or 60°, for example, or may be any angle in a rangeof 0<θ≦90°. The tool headstock 24 is mounted on the sliding surface 23 aso as to be slidable along the X axis. In the present embodiment, the Zaxis corresponds to the first axis, the X axis corresponds to the secondaxis, and the Y axis corresponds to the third axis.

As shown in FIG. 2, a tool spindle attachment portion 31 is formed atthe lower end of the tool headstock 24. In FIG. 3, the tool spindleattachment portion 31 is omitted for the convenience of the description.The tool spindle 25 is supported by the tool spindle attachment portion31 so as to be rotatable. The tool spindle 25 rotates around the axis O4which is perpendicular to the X-Z plane in the direction of the B axisin FIG. 2. The tool spindle 25 forms a portion of the main body of thetool headstock 24.

A B axis drive motor Mb (see FIG. 4) is incorporated into the toolheadstock 24. A power transmission means (not shown) made up of gears,shafts and the like is provided between the B axis drive motor Mb andthe tool spindle 25. The power transmission means transmits the powerfrom the B axis drive motor Mb to the tool spindle 25. As a result, thetool spindle 25 rotates around the axis O4 in the direction of the Baxis.

Furthermore, a fixture means (not shown) for fixing the tool spindle 25to the tool spindle attachment portion 31 or releasing the fixture isprovided between the tool spindle attachment portion 31 and the toolspindle 25. The power transmission means and the fixture means rotatethe tool spindle 25 in the direction of the B axis in FIG. 2 and at thesame time position the tool spindle 25 at a predetermined angle. Theaxis O1 of the tool spindle 25 is parallel to the sliding surface 23 aof the carriage 23, that is to say, the X axis.

Next, the turning tool holder 40 is described with reference to FIGS. 5and 6.

The turning tool holder 40 is provided with a holder main body 41. Amounting portion 42 in truncated cone form is formed in the proximal endportion of the holder main body 41. The holder main body 41 and themounting portion 42 are coaxially arranged. The holder main body 41 isattached to the tool spindle 25 via the mounting portion 42 so as to becoaxial with the axis O1 and removable.

As shown in FIGS. 5 and 6(A), an attachment groove 43 is provided on oneside surface of the holder main body 41. The attachment groove 43 has anopening facing the workpiece W. The surface which is in close proximityto the mounting portion 42 from among the inner surfaces of theattachment groove 43 is referred to as a turning tool attachment surface44. As shown in FIG. 5, the turning tool attachment surface 44 makes apredetermined angle θ relative to the axis of the holder main body 41.

The turning tool 45 is mounted in the attachment groove 43 of the holdermain body 41. The turning tool 45 is fixed to the lower end surface ofthe holder main body 41 using bolts 48. The distal end of the turningtool 45 protrudes from the attachment groove 43 along the horizontalline Yt. A turning tip 46 is provided at the distal end of turning tool45. The horizontal line Yt is a straight line included in both of theX-Y plane and the horizontal plane. The X-Y plane corresponds to a planewith the second and third axes.

Next, a control apparatus 100 is described with reference to FIG. 4.

A combined lathe apparatus 20 is provided with a control apparatus 100.As shown in FIG. 4, the control apparatus 100 has a main control section110 made of a CPU as control means. A process program memory 120, asystem program memory 130, a buffer memory 140, a process controlsection 150, an control panel 160 having a keyboard and the like, and adisplay portion 170 made of a liquid crystal display apparatus areconnected to the main control section 110 via a bus line 105.

An X axis control section 200, a Yt axis control section 210, a Z axiscontrol section 220 and a B axis control section 230 are connected tothe main control section 110 via the bus line 105. Each axis controlsection receives a move command relative to the axis from the maincontrol section 110. The respective axis control sections output themove command relative to axes to the drive circuits 202, 212, 222 and232. The respective drive circuits 202, 212, 222 and 232 receive thecorresponding move command and drive the motor of the axes (X, Yt, Z andB axis drive motors).

When an X axis drive motor Mx is driven, the tool spindle 25 moves alongthe X axis on the sliding surface 23 a of the carriage 23. When a Ytaxis drive motor Myt is driven, the carriage 23 moves along thehorizontal line Yt, and together with this, the tool spindle 25 alsomoves along the horizontal line Yt. When a Z axis drive motor Mz isdriven, the carriage 23 moves along the Z axis, and together with this,the tool spindle 25 also moves along the Z axis.

A workpiece spindle control section 240 is connected to the main controlsection 110 via the bus line 105. The workpiece spindle control section240 receives a rotation command from the main control section 110 andoutputs this rotation command to a drive circuit 242. The drive circuit242 receives the rotation command from the main control section 110 androtates the workpiece spindle drive motor M_(WS).

A tool spindle control section 250 is connected to the main controlsection 110 via the bus line 105. The tool spindle control section 250receives a rotation command from the main control section 110 andoutputs a spindle speed signal to a drive circuit 252. The drive circuit252 rotates a built-in type motor M_(TS) which is linked to the toolspindle 25 at a rotational speed corresponding to a rotation controlcommand on the basis of a spindle speed signal from the tool spindlecontrol section 250. As a result, the rotating tool unit rotatestogether with the tool spindle 25. The main control section 110 outputsa stop control command to the tool spindle control section 250 when aturning process tool is used. The tool spindle control section 250receives the stop control command from the main control section 110 andstops the motor M_(TS).

Next, the operation of the combined lathe apparatus 20 is described.

A turning tool holder 40 is attached to the tool spindle 25 for theconvenience of description. In addition, it is assumed that the axis O1of the tool spindle 25 rotates around the B axis in a direction parallelto the X axis, and the axis O1 is already positioned. The tool spindlecontrol section 250 stops the motor M_(TS) in this state. The controlapparatus 100 follows a process program stored in the process programmemory 120 and outputs an instruction to rotate to the workpiece spindlecontrol section 240, and rotates the workpiece spindle drive motorM_(WS).

In the control apparatus 100, the main control section 110 follows theabove described process program and outputs a move command to the X axiscontrol section 200. The X axis control section 200 outputs the movecommand to the drive circuit 202 and drives the X axis drive motorM_(X). As a result, the tool headstock 24 moves along the axis O1 of thetool spindle 25. As a result, as shown in FIG. 3, the blade of theturning tip 46 of the turning tool 45 is positioned in a straight lineincluded in a horizontal plane including the axis O2 of the workpiecespindle 26 a and the X-Y plane.

In this state, the main control section 110 outputs a move command tothe Yt axis control section 210. The Yt axis control section 210 outputsthe move command to the drive circuit 212. The drive circuit 212 drivesthe Yt axis drive motor Myt, and thus, the carriage 23 moves along thehorizontal line Yt, and together with this, the tool spindle 25 alsomoves along the horizontal line Yt. In addition, the main controlsection 110 follows the process program stored in the process programmemory 120 and outputs a move command to the Z axis control section 220.The Z axis control section 220 outputs the move command to the drivecircuit 222. The drive circuit 222 drives the Z axis drive motor M_(Z),and thus, the carriage 23 moves along the Z axis, and together withthis, the tool spindle 25 also moves along the Z axis.

As described above, when the tool spindle 25 moves along the horizontalline Yt, the workpiece W is cut along the horizontal line Yt by theturning process tool. In this state, the turning tip 46 of the turningtool 45 moves along the Z axis together with the tool spindle 25, andthus, a turning process is carried out on the workpiece W. The point atwhich the turning tip 46 carries out a cutting process on the workpieceW is referred to as cutting point. Accordingly, the workpiece W is cutalong the horizontal line Yt by the turning tool 45 when the cuttingpoint moves in the direction perpendicular to the Z axis.

As described above, the longer the workpiece W is, the more theworkpiece bends due to its own weight. Concerning this, in the presentembodiment, in the case where a turning process is carried out on theouter peripheral surface of the workpiece W, the workpiece bending dueto its own weight does not directly affect the precision in the process.That is to say, unlike with the prior art, the effects of the workpiecebending are avoided, even when the workpiece W is long.

In addition, the bed 21 is thin and extends along the horizontal lineYt. Therefore, it can be considered that the manner in which the bed 21bends may easily change in the vertical direction, in which the rigidityis low. This means that the pitching changes as shown in FIG. 15. In thepresent embodiment, however, the effects of pitching described above aresuppressed by cutting the workpiece W along the horizontal line Yt.

(Amount of Reduction Due to Bending of Workpiece W)

In the case where an iron material having a diameter of 100 mm×a lengthof 1270 mm is used as the workpiece W, the amount of bending δbecomes 20μm, as shown in the formula (1). Bending of the workpiece W becomes themaximum in the center portion of the workpiece W. Therefore, in the casewhere the height of the combined lathe apparatus is constant, the heightof the workpiece W becomes the least in the center portion of theworkpiece W. In the case where a turning process is carried out inaccordance with a conventional method, the cylindricity, which indicatesthe precision in the process of the workpiece W, becomes 40 μm and a bigproblem arises in terms of the precision of processing.

A calculation formula for obtaining the amount of reduction in thecylindricity due to the workpiece bending is shown below. FIG. 11 showsa method for turning a portion where the workpiece is bent and a portionwhere the workpiece is not bent. The amount of reduction A1 in thecylindricity due to the workpiece bending in the case where theworkpiece W is cut along the horizontal line Yt can be represented bythe following formula (2).

A1=(√{square root over (R ²+δ²)}−R)×2  (2)

In the case where the radius R of the workpiece W is 50 mm and δ is 20μm, A1 becomes 7.9 nm, as calculated using the above formula (2). Inaddition, in the case where cutting is carried out on a workpiece whichis in such a position as to be inclined by a cutting angle θk relativeto the horizontal line Yt, the amount of reduction A2 in thecylindricity due to the workpiece bending can be represented by thefollowing formula (3).

$\begin{matrix}{\begin{matrix}{{A\; 2} = {U - R}} \\{= {\left( {\sqrt{\left( {{{R \cdot \sin}\mspace{11mu} \theta \; k} + \delta} \right)^{2} + \left( \left( {{R \cdot \cos}\mspace{11mu} \theta \; k} \right)^{2} \right.} - R} \right) \times 2}}\end{matrix}\quad} & (3)\end{matrix}$

R: radius of a finished workpiece as instructed by a process program

δ: amount of bending in a portion where the workpiece is bent most (forexample, in the center of workpiece in the longitudinal direction)

U: the minimum distance between the center of the workpiece and theblade in a portion where the workpiece is bent most

In the case where the radius R of the workpiece W is 50 mm, δ is 20 μmand the cutting angle θk is 90 degrees, A2 becomes 40 μm as calculatedusing the above formula (3).

In addition, in the case where the radius R of the workpiece W is 50 mm,δ is 20 μm and the cutting angle θk is 60 degrees, A2 becomes 34 μm ascalculated using the above formula (3). In addition, in the case wherethe radius R of the workpiece W is 50 mm, δ is 20 μm and the cuttingangle θk is 45 degrees, A2 becomes 28 μm as calculated using the aboveformula (3). Thus, the amount of reduction in the cylindricity can bekept small to a negligible degree in accordance with the method forcutting the workpiece along the horizontal line Yt.

Next, error in the pitching is described with reference to FIG. 13. FIG.13 shows a case where a conventional turning method is used on aworkpiece W. The tool headstock moves along the vertical straight lineand the turning tool also moves along the vertical straight line. In ISO10791-1, for example, the allowance value of the precision in thepitching is defined as being within 60 μm per 1000 mm. In the case ofthe prior art shown in FIG. 13, change “Δ” in the location of the bladein the direction of the height can be represented by the followingformula.

Δ=L×cos θn−(L−60 μm)=L(cos θn−1)+60 μm

L: distance between sliding surface of carriage of bed 21 and blade ofturning tip 46 (μm)

θn: error in pitching (deviation in angle accompanying movement along Zaxis)

θn=tan(60/100,0000), and therefore, cos θn=0.999994, and when it isassumed that L=1000 mm from the actual machine size, for example, Δ=54μm. In the case of L=2000 mm, Δ=48 μm. In the case of Δ=54 μm, thecylindricity of the workpiece W after processing is 108 μm, which is abig problem.

A case where the combined lathe apparatus 20 shown in FIG. 12(A) is usedis described below. In the case where the workpiece W is cut along thehorizontal line Yt, the amount of reduction A3 in the cylindricity dueto the error in pitching can be represented by the following formula(4).

A3=(√{square root over (R ²+Δ²)}−R)×2  (4)

In the case where the radius R of the workpiece W is 50 mm and Δ=54 μm,A3 becomes 0.1 μm as calculated using the above formula (4). Inaddition, in the case where the workpiece is cut in such a position asto be inclined by the cutting angle θk relative to the horizontal lineYt, the amount of reduction A4 in the cylindricity due to error inpitching can be represented by the following formula (5).

A4=(√{square root over (R·sin θk+Δ)²+(R·cos θk)²)}{square root over(R·sin θk+Δ)²+(R·cos θk)²)}−R)×2  (5)

In the case where the radius R of the workpiece W is 50 mm, Δ is 54 μmand the cutting angle θk is 60 degrees, A4 becomes 92 μm as calculatedusing the above formula (5). Thus, the amount of reduction A3 is sosmall as to be negligible, as compared to A4.

Next, thermal displacement is described.

Thermal displacement occurs in the tool spindle 25 and the rotating toolin the direction of the axes, due to heat emitted from the motor M_(TS)and the bearing. In this case, the turning process tool is indirectlysubjected to the effects of heat from the motor M_(TS) and the bearing,even after the rotating tool unit is changed to the turning processtool.

FIG. 18 shows the internal structure of the tool spindle 25.

As shown in FIG. 18, a stator 37 is provided on the inner surface of anexternal cylinder 35 in such a manner as to surround a rotor 32. Therotor 32 is supported with bearings 33 and 34 in such a manner as to berotatable relative to the external cylinder 35. In addition, a toolunit, for example a rotating tool unit, is attached to a distal end ofthe rotor 32. In addition, a cooling circuit 36 is incorporated in theexternal cylinder 35. A liquid of which the temperature is controlledflows through the cooling circuit 36. Therefore, “thermal displacementin a direction perpendicular to the axis of the tool spindle 25” isgenerally kept smaller than the “thermal displacement in the directionof the axis of the tool spindle 25.” The arrows in FIG. 18 indicate thedirection of thermal displacement.

Next, thermal displacement which occurs along the axis of the toolspindle 25 and thermal displacement which occurs in a directionperpendicular to the axis are addressed. FIG. 16 is a graph showing therelationship between the amount of thermal displacement which occursalong the axis of the tool spindle 25 and the amount of thermaldisplacement which occurs in the direction perpendicular to the axis ofthe tool spindle 25. As shown in FIG. 16, thermal displacement whichoccurs along the axis of the tool spindle 25 becomes greater than thethermal displacement which occurs in a direction perpendicular to theaxis as the temperature of the tool headstock 24 increases. Therefore,thermal displacement which occurs along the axis of the tool spindle 25affects the turning process tool attached to the tool spindle 25.

In the following, the effects of thermal displacement are describedusing concrete numbers. In this description, as shown in FIG. 16, theamount of thermal displacement along the axis of the tool spindle 25 is35 μm (=δ₁) and the amount of thermal displacement in a directionperpendicular to the axis of the tool spindle 25 is 6 μm (=δ₂) when thetemperature of the tool spindle 25 is 29° C. As shown in FIGS. 17(A) and17(B), when a turning process is carried out on the outer peripheralsurface of the workpiece W so that the outer diameter of the workpiece Wbecomes R=50 mm after processing, a case where the workpiece is cut at apredetermined angle θ as in the prior art and a case where a turningprocess is carried out on the workpiece W along a horizontal line as inthe present embodiment are compared.

The radius R₁ of the workpiece W after processing in the case where aconventional method is used can be calculated using the followingformula.

R ₁=√{square root over ((R−δ ₁)²+δ₂ ²)}.

The radius R₁ of the workpiece W after processing in this case isR₁=49.965 (mm), irrespectively of θ in the combined lathe apparatus 20.Accordingly, in this case, R−R₁=35 (μm), and there is an error of 35 μm,irrespectively of the angle θ.

Meanwhile, in the case where a turning process is carried out on theworkpiece W along the horizontal line, as in the present embodiment, theradius of workpiece after processing can be calculated using thefollowing formula, when θ=60° in the combined lathe apparatus 20.

R ₂=√{square root over ((R−(δ₁ cos θ+δ₂ sin θ))²+(δ₁ sin θ−δ₂ cosθ)²)}{square root over ((R−(δ₁ cos θ+δ₂ sin θ))²+(δ₁ sin θ−δ₂ cos θ)²)}

Here, R₂=49.977 (mm) when θ=60°.

Accordingly, there is an error of R−R₂=23 (μm).

In addition, when θ=45°, R₂=49.971 (mm).

Accordingly, there is an error of R−R₂=29 (μm).

In addition, when θ=90°, R₂=49.994 (mm).

Accordingly, there is an error of R−R₂=6 (μm).

As described above, in the case where a turning process is carried outhorizontally on a workpiece, the effects of thermal displacement aremade smaller than in the case where a conventional method is used.

As described above, in the present embodiment, a turning process iscarried out on the workpiece W, which is attached to the workpiecespindle 26 a, by moving the carriage 23 in a direction including the Yaxis component, so that the cutting point of the turning process toolmoves along the horizontal line Yt. As a result, the effects of theworkpiece W bending due to its own weight, the effects of pitching andthe effects of thermal displacement due to the motor and the bearingsare simultaneously suppressed.

In addition, as shown in FIG. 5, in the turning tool holder 40 in thepresent embodiment, the angle formed between the surface 44 to which theturning tool is attached and the axis of the holder main body 41 is thesame as the predetermined angle θ formed between the axis O1 of the toolspindle 25 and the horizontal surface 21 a. As a result, a method forcontrolling the combined lathe apparatus 20 having an ATC 30, as well asa turning tool holder which can be used for combined lathe apparatuseshaving an ATC 30, are provided.

Second Embodiment

According to the prior art, a turning process is carried out on aworkpiece W in the cutting location shown in FIG. 6(B) and in the X-Zplane. At this time, the blade of the turning process tool is located inthe X-Z plane, which includes the center around which the workpiece Wrotates, and along the axis O1 of the tool spindle 25. Positioning ofthe turning process tool in this location is referred to as core heightadjustment. This core height adjustment is known to have an effect onthe precision in processing and the quality of the processed surface. Aturning tool is attached to the turning tool holder, and a turning tipis attached to the turning tool. The thickness Th of commerciallyavailable turning tools, to which a turning tip is attached, is usuallystandardized. The turning tool holder is designed taking the thicknessTh of the turning tool into consideration so that the blade of theturning tool coincides with the axis O2 of the workpiece spindle 26 a.That is to say, the turning tool holder is fabricated so as to bepositioned in the X-Z plane at the time of the turning process. Thus,the turning process tool is positioned, and therefore, it is notnecessary for the operator to carry out the above described core heightadjustment in the case where a turning process is carried out on theworkpiece W.

In the case where a turning process is carried out in the combined latheapparatus 20 according to the first embodiment, however, as shown inFIG. 6(B), it is necessary to position the turning process tool so thatthe blade of the turning tip 46 coincides with the “horizontal axisperpendicular to the axis O2 of the workpiece W.” It is necessary forthe operator to carefully carry out this core height adjustment.Concretely, it is necessary to add a program for positioning the X and Yaxes in order to carry out the core height adjustment. At this time, inorder to check whether the core height adjustment has been carried outcorrectly, an end surface of a workpiece W is cut using the process toolof which the core height has been adjusted, and the above describedprogram is finely adjusted until there is no area left uncut on the endsurface of the workpiece W. At this time, the end surface of theworkpiece W is cut repeatedly, and therefore, a problem arises that ittakes a tremendous amount of time and effort.

As means for solving this problem, it is desirable to provide a bladeposition registering apparatus 60 with the combined lathe apparatus 20in addition to the combined lathe apparatus 20 and the turning toolholder 40 in the first embodiment.

The configuration of the blade position registering apparatus 60 isdescribed below with reference to FIGS. 1 to 7, 19 and 20. In the secondembodiment, a blade position registering apparatus 60 is additionallyprovided in the configuration of the first embodiment. Accordingly, thesame symbols are attached to the same components as in the firstembodiment, and the descriptions thereof are omitted.

As shown in FIG. 4, the blade position registering apparatus 60 isprovided with a control panel 160 and a buffer memory 140. The controlpanel 160 corresponds to the blade position inputting means, and thebuffer memory 140 corresponds to a storage means.

As shown in FIG. 19, the operator operates the control panel 160 anddisplays a tool registering screen 171 on the display portion 170. Theoperator inputs a string of letters “TOOL-C,” for example, into the toolname field as the tool name. In addition, the operator inputs “tool forturning X-Z plane,” “tool for horizontal turning,” or a name of anothertool, such as a rotating tool, in the tool type field. As shown in FIG.20(B), a tool length entry field 172 for a tool for horizontal turningis displayed on the screen of the display portion 170. The operatorinputs a first tool length Ca, a second tool length Cb and a third toollength Cc, respectively, into the entry field “TOOL-C” of the toollength entry field 172. The main control section 110 stores the inputtedtool length in the buffer memory 140.

As shown in FIGS. 6(A) and 6(B), the first tool length Ca is the amountof offset by which the blade of the turning tip 46 is offset along theaxis O2 of the workpiece spindle 26 a from the reference point PS alongthe axis O1 of the tool spindle 25. The reference point PS is in apredetermined location along the axis O1 of the tool spindle 25.Although in the present embodiment the intersection of the end surfaceof the tool spindle 25 and the axis O1 of the tool spindle 25 is thereference point PS, the invention is not limited to this. That is tosay, the reference point PS may be in any location that can be easilyspecified along the axis O1 of the tool spindle 25. The first toollength Ca corresponds to a conventional tool length B. The tool length Bcorresponds to a fourth tool length. The tool length B is the amount ofoffset by which the blade of the conventional turning tool is offsetalong the axis O2 of the workpiece spindle 26 a from the reference pointPS along the axis O1 of the tool spindle 25.

The second tool length Cb is the amount of offset by which the blade ofthe turning tip 46 is offset along the horizontal line Yt from thereference point PS. The second tool length Cb is used to correct thediameter of the processed workpiece W and changed depending on thelength of the turning tool to be used and the manner in which theturning tool to be used protrudes.

The third tool length Cc is the amount of offset by which the blade ofthe turning tip 46 is offset in the vertical direction from thereference point PS. The third tool length Cc is the distance between theabove described reference point PS and the blade of the turning tip 46in the vertical direction. As shown in FIG. 7, the location of thisreference point relative to the center of rotation of the workpiece W,that is to say, the original point within the machine, is already known.According to the prior art, the first tool length Ca, the second toollength Cb and the third tool length Cc are registered, and they are notused at the time when a workpiece is processed.

An example where the main control section 110 carries out an internalarithmetic processing using the location of the blade stored in thebuffer memory 140 (storage means), that is to say, the second toollength Cb, the third tool length Cc and the predetermined angle θ, isdescribed below. This example is an example where the second tool lengthCb, the third tool length Cc and the predetermined angle θ are used togain the tool length α and β in the direction of the X axis and the Yaxis, which are used in general tool length correcting functions.

The following formulas are derived from FIG. 7:

M×sin=Cc  (6)

M×cos θ+G=Cb  (7)

G×cos θ+M=α  (8)

M: the distance between the point T1 at which the horizontal plane whichpasses through the blade of the turning tip 46 crosses the axis O1 ofthe tool spindle 25 and the reference point PS along the axis O1

G: the distance between the blade of the turning tip 46 and the abovedescribed point T1

Here, the following formula is derived from formula (6):

M=Cc/(sin θ)  (9)

Formula (9) is substituted into formula (7) in order to obtain:

(cos θ/sin)×Cc+G=Cb  (10)

Accordingly,

G=Cb−(cos θ/sin)×Cc  (11)

Formula (9) and formula (11) are substituted into formula (8) in orderto obtain:

α=(Cb−(cos θ/sin)×Cc)×cos θ+Cc/sin  (12)

As shown in formula (12), the tool length α that has been used accordingto the prior art in the combined lathe apparatus 20 having the X axisand the Y axis in the mechanical coordinate can be represented using thesecond tool length Cb, the third tool length Cc, and the predeterminedangle θ. The tool length α corresponds to the fifth tool length. Thetool length α is the amount of offset by which the blade of the turningtip is offset along the X axis from the reference point PS.

In addition, the following formula is derived from FIG. 7:

β=G×sin θ

Formula (11) is substituted into the above formula in order to obtain:

β=(Cb−(cos θ/sin θ)×Cc))×sin θ  (13)

In the case of the prior art, the following formulas are derived whenassuming that the distance in which the blade moves along the X axis isthe diameter D of the workpiece W as the program instructs.

Amount of movement in X direction=L−BA−α−(D/2)  (14)

Amount of movement in Y direction=0  (15)

In the present embodiment, it is required to position the tool inposition 1 in FIG. 7 in order to adjust the core height. In addition, inorder to carry out a cutting process in the Y′-Z plane, the tool ispositioned in accordance with the following formulas (16) and (17) usingα and β, which are obtained from formulas (12) and (13). The controlapparatus 100 operates in accordance with formulas (12), (13), (16) and(17).

Amount of movement in X direction (horizontalturning)=L−BA−α−(D/2)+K=L−BA−α−(D/2)+((D/2)−(D/2)×cos θ)  (16)

Amount of movement in Y direction (horizontal turning)=β+J=β+(D/2)×sinθ  (17)

L and BA are mechanical parameters and have already known values whichare set when the machine manufacturer assembles the machine.

L: the distance between the original point of machine and the center ofrotation of the workpiece W (axis O2)

BA: the distance between the original point of machine when the toolspindle 25 returns to the original point and the end surface of the toolspindle 25 (reference point PS)

D: the diameter of the workpiece which is instructed by the program

Although the description is omitted, the first tool length Ca isreferred to in the same manner as in the conventional tool lengthcorrection when the tool moves along the Z axis. As can be seen from theabove described formulas, the operator may simply input the diameter ofthe workpiece W as in the prior art. That is to say, when the first toollength Ca, the second tool length Cb, the third tool length Cc and thepredetermined angle θ are used in the process program for conventionaltwo-axis lathing that has been programmed such that the blade movesalong the X axis and the Z axis, the amounts of movement of the bladealong the X axis, the Y axis and the Z axis can be gained.

The blade position registering apparatus 60 according to the secondembodiment provides a blade position registering apparatus which can beused in the combined lathe apparatus according to the first embodimenthaving an ATC 30. In the case where high precision in processing is notrequired, in the case where the workpiece W is short or in the casewhere effects of the workpiece due to its own weight are small, theconventional turning process may be adopted.

In the case where the conventional turning process is carried out, theoperator inputs a tool for X-Z plane turning as the tool type whenregistering the tool name “TOOL-A,” “TOOL-B” or the like on the toolregistering screen 171 shown in FIG. 19. The “TOOL-A,” “TOOL-B” or thelike for X-Z plane turning correspond to the tool for the secondaxis-first axis plane turning.

In addition, as shown in FIG. 20(A), the main control section 110displays the tool length entry field 173 for a tool for X-Z planeturning on the display screen in the display portion 170. The operatoroperates the control panel 160 so that the Z axis offset and the X axisoffset are respectively inputted into the fields corresponding to the“TOOL-A” and “TOOL-B” in the tool length entry field 173. The maincontrol section 110 stores the inputted tool length in the buffer memory140. In the present embodiment, the Z axis offset corresponds to thetool length B, which is the fourth tool length, and the X axis offsetcorresponds to the tool length α, which is the fifth tool length. Inaddition, the control panel 160 corresponds to the input means forinputting the fourth tool length and the fifth tool length, and thebuffer memory 140 corresponds to the means for storing the inputted toollengths.

This combined lathe apparatus having a blade position registeringapparatus selects a tool for X-Z plane turning as the tool to be usedwhich is designated in the process program and inputs the tool length B(fourth tool length) and the tool length α (fifth tool length) of theturning tool attached to the conventional turning process tool holder,and thus, can carry out the same turning process as in the prior art.

As described above, the control apparatus 100 automatically determineswhether the tool name that has been programmed so that the blade movesalong the X axis and the Z axis should be used as it is from among thetool names that have been designated as tools used in the processprogram in accordance with the tool type that has been inputted on thetool registering screen 171, and thus, tool movement control should becarried out along the X axis and the Z axis or the first tool length Ca,the second tool length Cb, the third tool length Cc and thepredetermined angle θ should be used so that tool movement control iscarried out along the X axis, the Y axis and the Z axis.

Third Embodiment

Next, the blade position detecting apparatus 50 which is used in theabove described combined lathe apparatus 20 is described with referenceto FIGS. 1 and 8 to 10.

A support portion 53 is provided in the vicinity of the workpiecespindle 26 a, above a bed 21. An arm 51 which extends along the Z axisis supported by the support portion 53 in such a manner as to berotatable. A detection portion main body 52 which is used for a combinedlathe apparatus 20 is provided at a distal end of the arm 51. Thedetection portion main body 52 is placed in the vicinity of the axis O2of the workpiece spindle 26 a. The support portion 53 is omitted in FIG.8. The arm 51 is rotated by the support portion 53 when a turningprocess is carried out on the workpiece W, so that the detection portionmain body 52 stands by outside the region where the main body is to beprocessed.

A main body case 54 is attached to the arm 51. A needle member 55 issupported within the main body case 54 in such a manner as to bereciprocable against the pressing force of an elastic member (notshown). In addition, as shown in FIG. 10, the needle member 55 issupported in such a manner as not to be rotatable around its axis O3. Asshown in FIGS. 8 and 9, a distal end of the needle member 55 protrudesfrom the upper surface of the main body case 54. Three pairs ofconnection terminals 56 are placed with equal angular intervals aroundthe axis O3 of the needle member 55 on the inner surface of the upperwall 54 a of the main body case 54. As shown in FIG. 10, threecontactors 57 which always make contact with the three pairs ofconnection terminals 56 protrude from the end portion of the needlemember 55.

When the needle member 55 reciprocates, one of the three pairs ofconnection terminals 56 moves away from the contactors 57, so that theelectrical connection between the pairs of connection terminals 56 andthe contactors 57 is broken. The three pairs of connection terminals 56are connected to each other in series, and therefore, when one of thethree pairs of connection terminals 56 is electrically disconnected, anOFF detection signal is outputted to the control apparatus 100. Adetection body 58 is supported by the distal end of the needle member 55via a bent portion 55 a in L shape. As shown in FIG. 8, the detectionbody 58 is formed in polyhedron block form. The detection body 58 isprovided with a first detection surface 58 a, a second detection surface58 b, a third detection surface 58 c, and a fourth detection surface 58d.

As shown in FIGS. 8 and 9, the first detection surface 58 a is a planeperpendicular to the axis O2 of the workpiece spindle 26 a. Thedetection body 58 is provided with a pair of first detection surfaces 58a which are aligned along the Z axis. The pair of first detectionsurfaces 58 a can make contact with the blade of the turning tip 46 whenthe tool is moved along the axis O2 of the workpiece spindle 26 a. Thefirst detection surfaces 58 a measure the first tool length Ca.

When the turning tip 46 moves along the +Z axis or −Z axis so as to makecontact with a first detection surface 58 a, a detection signal isoutputted to the control apparatus 100 from the detection portion mainbody 52. The Z axis drive motor Mz stops rotating at the same time asthe output of this detection signal. At this time, the amount ofmovement of the tool from the initial location Z0, not shown, is countedin accordance with the number of revolutions of the motor, so that thecoordinates of the location where the tool stops along the Z axis iscalculated. The control apparatus 100 calculates the first tool lengthCa on the basis of the calculated location at the coordinates. Thecontrol apparatus 100 is provided with a counter for counting the amountof movement of the tool.

When the turning tool attached to conventional tool holders moves, thefirst detection surface 58 a can make contact with the blade of theturning tip. That is to say, the first detection surface 58 a can beused to detect the tool length B of the turning tool attached toconventional tool holders.

The second detection surface 58 b is a plane perpendicular to thehorizontal line Yt. The detection body 58 is provided with a pair ofsecond detection surfaces 58 b which are arranged so as to face eachother. The pair of second detection surfaces 58 b can make contact withthe blade of the turning tip 46 when the tool is moved along thehorizontal line Yt. The second detection surfaces 58 b measure thesecond tool length Cb.

When the turning tip 46 moves along the horizontal line Yt and makescontact with a second detection surface 58 b, a detection signal isoutputted to the control apparatus 100 from the detection portion mainbody 52. The Yt axis drive motor Myt stops rotating at the same time asthe output of this detection signal. At this time, the amount ofmovement of the tool from the initial location Yt0, not shown, iscounted in accordance with the number of rotations of the motor, so thatthe coordinates of the location where the tool stops along the Yt axiscan be calculated. The control apparatus 100 calculates the second toollength Cb on the basis of the calculated location at the coordinates.

Third detection surfaces 58 c are horizontal planes perpendicular to avertical line. The detection body 58 is provided with a pair of thirddetection surfaces 58 c which are arranged in such a manner as to faceeach other. When the tool is moved along a vertical line, the pair ofthird detection surfaces 58 c can make contact with the blade of theturning tip 46. The third detection surfaces 58 c measure the third toollength Cc.

When the turning tip 46 moves along a vertical line and makes contactwith a third detection surface 58 c, a detection signal is outputted tothe control apparatus 100 from the detection portion main body 52. The Xaxis drive motor Mx and the Yt axis drive motor Myt both stop rotatingat the same time as the output of this detection signal. At this time,the amount of movement of the tool from the initial location X0 and theinitial location Yt0 is counted in accordance with the number ofrotations of the motors, so that, the coordinates of the location wherethe tool stops is calculated. The control apparatus 100 calculates thethird tool length Cc on the basis of the calculated location at thecoordinates.

Fourth detection surfaces 58 d are planes perpendicular to the X axis.The detection body 58 is provided with a pair of fourth detectionsurfaces 58 d which are arranged in such a manner as to face each other.When the turning tool attached to conventional tool holders moves alongthe X axis, the pair of fourth detection surfaces 58 d can make contactwith the blade of the turning tip. That is to say, the fourth detectionsurfaces 58 d are used to measure the tool length a of the turning toolattached to conventional tool holders.

When the turning tip 46 moves along the X axis and makes contact with afourth detection surface 58 d, a detection signal is outputted to thecontrol apparatus 100 from the detection portion main body 52. The Xaxis drive motor Mx stops rotating at the same time as the output ofthis detection signal. At this time, the amount of movement of the toolfrom the initial location X0 is counted in accordance with the number ofrotations of the motor, so that the coordinates of the location wherethe tool stops can be calculated. The control apparatus 100 calculatesthe tool length α on the basis of the calculated location at thecoordinates.

The detection body 58 is provided with a pair of first detectionsurfaces 58 a, a pair of second detection surfaces 58 b, a pair of thirddetection surfaces 58 c, and a pair of fourth detection surfaces 58 d.As a result, the location of the blade of the tool can be detected inaccordance with the position and form of the tool attached to the toolholder.

In the blade position detecting apparatus 50 according to the presentembodiment, the detection body 58 is provided with second detectionsurfaces 58 b and third detection surfaces 58 c for measuring the secondtool length Cb and the third tool length Cc. Therefore, the second toollength Cb and the third tool length Cc can be measured. In addition, thedetection body 58 is also provided with first detection surfaces 58 aand fourth detection surfaces 58 d. Therefore, the first tool length Ca,that is to say, the tool length B of the turning tool attached toconventional tool holders and the conventional tool length α can also bemeasured.

The present embodiments may also be implemented as follows.

Although the first embodiment of the present invention is implemented asthe combined lathe apparatus 20 as shown in FIG. 12(A), the firstembodiment may be implemented as the combined lathe apparatus as shownin FIG. 12(B). In this case, the carriage 23 is moved in a directionincluding the Y axis component, in order to move the tool attached tothe tool spindle 25 along the horizontal line Yt, and at the same time,the tool headstock 24 is moved along the X axis. In addition, thecombined lathe apparatus is provided with a control apparatus 100 whichcarries out a turning process on the workpiece W which is attached tothe workpiece spindle 26 a. In this case, the tool moves by Y cos θ/sinθ along the X axis, and by Yt sin θ along the Y axis. As a result, thecarriage 23 moves along the horizontal line Yt.

In addition, the present invention may be embodied as the combined latheapparatus shown in FIG. 12(C). This case corresponds to a case where θis 90 degrees and the Y axis coincides with the horizontal line Yt.

1. A combined lathe apparatus, comprising: a workpiece spindle on whicha workpiece is mounted; a tool spindle to which a turning process toolfor carrying out a turning process on the workpiece is removablyattached; automatic tool replacing means for taking out a specificturning process tool from among a plurality of turning process tools andreplacing the turning process tool attached to the tool spindle with thespecific turning process tool; a movable body which is movable along asecond axis which is perpendicular to a first axis that is the axis ofthe workpiece spindle and forms a predetermined angle θ (0<θ≦90°) with ahorizontal plane; a tool headstock supported by the movable body, thetool headstock having the tool spindle; and control means forcontrolling movement of the movable body, wherein the movable body ismovable in a direction including a third axis component which isperpendicular to the first axis and second axis, wherein the toolspindle can be controlled to be rotated or held without being rotated,and wherein the control means carries out a turning process on theworkpiece attached to the workpiece spindle by moving the movable bodyin a direction including the third axis component in order to move thecutting point of the turning process tool attached to the tool spindlealong a horizontal line which is perpendicular to the first axis, or bymoving the movable body in a direction including the third axiscomponent, and at the same time, moving the tool headstock along thesecond axis; and a blade position detecting apparatus which is providedin the combined lathe apparatus which has a plurality of detectionsurfaces which can make contact with the blade of the turning processtool, and outputs a detection signal when the blade makes contact withone of the detection surfaces, the blade position detecting apparatuscomprising: a first detection surface for detecting the blade of theturning process tool which moves along the axis of the workpiecespindle; a second detection surface for detecting the blade of theturning process tool which moves along a horizontal line that isperpendicular to the axis of the workpiece spindle; and a thirddetection surface for detecting the blade of the turning process toolwhich moves along a vertical line.
 2. The apparatus of claim 1, furthercomprising: a fourth detection surface for detecting contact with theblade of the turning process tool which moves along the second axis.